D K Chakrabarty
Articles written in Journal of Chemical Sciences
Volume 87 Issue 4 April 1978 pp 133-139 Dehydrogenation
Solid state properties of lithium doped nickel oxide samples and their catalytic activity towards isopropanol (IPA) decomposition have been studied. Electrical resistivity, surface area and lattice parameter decrease with doping which is due to substitutional incorporation of Li into the nickel oxide lattice. IPA undergoes only dehydrogenation on all the samples, dehydrogenation activity increasing with increased doping. There is a small but regular decrease in the Arrhenius activation energy with doping. The increase in catalytic activity on doping is attributed to the increase in hole concentration which is likely to favour the desorption of acetone, the rate determining step of the reaction.
Volume 89 Issue 2 April 1980 pp 131-137 Physical and Theoretical
Decomposition of 2-propanol has been studied on vanadium pentoxide with MoO3 and WO3 additives. It has been observed that a small amount of the additives increases the dehydration activity of the catalysts, but at 5% or higher concentration, dehydration of 2-propanol decreases. The initial increase followed by a decrease in the dehydration activity with increased amount of additives is due to the change in the rate-determining step. Addition of MoO3, WO3, and alkali metal oxides to vanadium pentoxide has similar effects on the V4+ concentration and catalytic activity. Based on the results of the kinetic and ESR spectral studies, a scheme for the reaction has been proposed. It is concluded that the concentration of V4+ ion plays the crucial role in these catalysts.
Volume 89 Issue 6 December 1980 pp 533-538 Physical and Theoretical
The reduction of α-Fe2O3 and Li0.5Fe2.5O4 by hydrogen has been studied to characterise the stages of reduction. The course of reduction as followed by TGA and Mössbauer spectroscopy indicates that (i) in the case of α-Fe2O3, the reduction to metallic iron goes through the intermediate formation of Fe3O4, and (ii) in the case of Li0.5Fe2.5O4 the reduction proceeds in a single step to give a mixture of LiFeO2 and Fe.
Volume 90 Issue 4 August 1981 pp 339-342 Inorganic and Analytical
Monophasic compounds with composition Fe1−x Cux Cr2Se4 (0≤x≤0·2) have been prepared. The compounds have defect nickel arsenide structure. The compositions are semiconductors with low energy of activation. Their Seebeck coefficients are temperature-independent. The compositions x=0 and 0·1 show temperature independent paramagnetism except for a small hump around 210 K. The peculiar behaviour of the susceptibility-temperature plot for the composition x=0·2 is not understood.
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